This invention relates to a rotary hammer drill, and particularly to an adaptor for attaching a bit to the drill.
Concrete or rock is drilled using a rotary hammer drill having a bit which is both reciprocated and rotated. A conventional rotary hammer drill has a bit secured directly to a chuck on the drive shaft of the drill. The forward end of the shaft engages with the rear end of the bit to transmit the hammering force from the drill to the bit.
Generally in a rotary hammer drill, the rotational speed is variable, but the hammering force is not adjustable. Consequently if the bit is thin, it may be broken by an excessively strong hammering force.